1. Field of Invention
This invention relates to perimeter weighted iron type golf club heads, and more particularly, to perimeter weighted iron type golf club heads having a rear cavity containing a gradated secondary weight system.
2. Description of the Prior Art
It has been common practice in recent years to provide iron type golf club heads with perimeter weighting by forming a cavity on the back side of the club head. Distributing the major portion of the club head weight around the perimeter of the club head results in a lower center of gravity and increased polar moment of inertia (PMI) for the club. The lower center of gravity has the effect of increasing the trajectory of the resultant ball flight and making the lower lofted irons easier to hit. The increased polar moment of inertia causes the club head to resist twisting at the moment of impact with a ball during an off center hit, resulting in a more forgiving club. This feature has been a boon to encouraging newer players to participate in the sport.
Unfortunately, lowering the center of gravity also increases the ball trajectory for the higher lofted clubs. This increased altitude causes the ball to be more susceptible to effects of the wind, and a subsequent loss in precision for golf players. The increased polar moment of inertia makes it harder for the better player to "work" the ball advantageously in his short game. It also has the undesirable effect of reducing the club head "sweet spot", which in turn reduces the amount of positive feedback the player receives. In general, expertly and poorly struck balls feel the same to the player. This lack of differentiation deprives the player of information needed to continue to improve his game skill.
In order to overcome the basic disadvantages of perimeter weighted golf clubs, many attempts have been made to improve the weight distribution by including in the rear cavity formed by the perimeter weighting some type of auxiliary weighting of various structural forms. Pertinent examples of this type of golf club head are disclosed in U.S. Pat. Nos. 4,826,172; 4,907,806; 4,919,430; 5,014,993; 5,048,834; 5,242,167; 5,328,184 and 5,395,113 to Antonious, and U.S. Pat. No. 5,333,872 to Manning et al;. Also, U.S. Design Pat. Nos. 328,322 and 363,332 show similar perimeter weighted golf club head designs.
The present invention enhances the positive aspects while reducing undesirable side effects of perimeter weighted iron type golf club heads with a back cavity and additional gradated weight members provided within the cavity.